The de-leading of America

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This entry was posted on January 3, 2013 at 3:09 pm and is filed under crimes, environment, science and medicine.
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9 Responses to “The de-leading of America”

Stormcrowsaid

“Science” articles like this make me furious. I’m hot up to the red mark as I’m writing this.

The parent article in Mother Jones made the initial mistake, which was to implicitly assume that correlation implied causation.

Note that the author, Kevin Drum, didn’t have the stones to actually <tell the reader explicitly that he was doing this.

After reading this, I’m not going to buy a causal link until and unless I’ve seen, at minimum, an abstract of a refereed journal article which shows the biochemistry.

Getting lead out of the human environment is a damned good idea, but I’ll be damned myself before I’ll accept somebody “lying for Jesus”.

“Ends” and “means” are not separate, they are intimately connected with one another. Shakespeare said this a hell of a lot more eloquently than I’ll ever be able to do; watch “Macbeth” thoughtfully and you’ll see it.

I think you’re jumping too quickly, Stormcrow. Kevin said this in the original article, making it clear that he does understand the correlation/causation story:

What’s more, a single correlation between two curves isn’t all that impressive, econometrically speaking. Sales of vinyl LPs rose in the postwar period too, and then declined in the ’80s and ’90s. Lots of things follow a pattern like that. So no matter how good the fit, if you only have a single correlation it might just be a coincidence. You need to do something more to establish causality.

Do a half dozen articles prove the case? No, of course not. But it does mean that this is not an issue to get hot under the collar about. There is evidence for the hypothesis. And the correlation is a necessary condition for proof, though not a sufficient one.

Stormcrowsaid

Wright et al. gets closer to nailing down a causal relationship. But the other works you cite (with the exception of Davies, which examines mortality rather than behavior) are quite clear about what they’re claiming they’ve demonstrated, which is an “association”, not a “causal relationship”.

Stormcrow, Davies showed excess deaths from violence. While of course getting killed is not a violent act, one very good way to get killed is to engage in violence against others.

Demonstrating a clear causal link between a chemical event and a complex behavior is asking a lot. I don’t think that the exact biochemistry of how lead lowers IQ has been established, but the association is unambiguous. I don’t think anyone could tell you which of dozens of carcinogens in tobacco caused a particular lung cancer. Reasoning in medicine is subtly different from reasoning in classical physics.

You’re welcome not to believe that causation has been proven. But I think getting furious over what is a well-established hypothesis is a waste of indignation.

For a long time I’ve been wondering why, considering that most crime has historically resulted from economic need more than any other factor, that crime rates in the US have gone down even as income inequality has gone up and most Americans are poorer than their parents were forty years ago.

This helps fill in part of the answer. And as Kevin Drum notes, it’s been known for decades that lead poisoning is probably the biggest factor in African-Americans having lower overall IQ scores than their white counterparts. Lead poisoning also leads to increases in aggression. From a transcript of a 2006 NPR program, “Lead Poisoning and Black Children”:

We’ve known about the dangers of lead forever. Roman emperor Nero was poisoned by lead, after all. We know that the substance is extremely toxic, especially to developing young brains. It only takes a tiny hint of lead, the size of a sugar speck really, to cause learning and behavioral problems, stunted growth, aggression and memory and hearing loss, particularly among kids and developing fetuses. A Colorado State University researcher called the relationship between lead and low academic test scores, quote, “so extreme it’s almost beyond belief,” end quote.

The fact that there is still lots of lead lurking in the inner-city environment — mostly from older houses whose owners could never afford (or couldn’t be bothered, if they were slumlords) to properly remove the lead paint from both interiors and exteriors — likely helps explain (along with the worsening economic situation over the past forty years) why the amount of violent crime hasn’t dropped in exact sync with the end of leaded gas.

Stormcrowsaid

For a long time I’ve been wondering why, considering that most crime has historically resulted from economic need more than any other factor, that crime rates in the US have gone down even as income inequality has gone up and most Americans are poorer than their parents were forty years ago.

And the association I’ve heard most frequently invoked to explain this is demographic: the overall age distribution is tilting to higher age groups.

Roman emperor Nero was poisoned by lead, after all.

He was also the 5’th generation of the Julio-Claudian dynasty, and he grew up in a snakepit.

Look, I’m not arguing with the takeaway, which is that we should have dealt with environmental lead levels two godforsaken generations ago.

What pisses me off is that some people seem to be willing to sacrifice scientific thinking on the altar of sound public policy. And that’s unsound; it’s hard enough to try to get the notion of what science even is across to the citizens of the Idiocracy.

Pregnant women were recruited from four prenatal clinics in Cincinnati, Ohio if they resided in areas of the city with a high concentration of older, lead-contaminated housing. We studied 250 individuals, 19 to 24 y of age, out of 376 children who were recruited at birth between 1979 and 1984. Prenatal maternal blood lead concentrations were measured during the first or early second trimester of pregnancy. Childhood blood lead concentrations were measured on a quarterly and biannual basis through 6.5 y. Study participants were examined at an inner-city pediatric clinic and the Cincinnati Children’s Hospital Medical Center in Cincinnati, Ohio. Total arrests and arrests for offenses involving violence were collected from official Hamilton County, Ohio criminal justice records. Main outcomes were the covariate-adjusted rate ratios (RR) for total arrests and arrests for violent crimes associated with each 5 microg/dl (0.24 micromol/l) increase in blood lead concentration. Adjusted total arrest rates were greater for each 5 microg/dl (0.24 micromol/l) increase in blood lead concentration: RR = 1.40 (95% confidence interval [CI] 1.07-1.85) for prenatal blood lead, 1.07 (95% CI 0.88-1.29) for average childhood blood lead, and 1.27 (95% CI 1.03-1.57) for 6-year blood lead. Adjusted arrest rates for violent crimes were also greater for each 5 microg/dl increase in blood lead: RR = 1.34 (95% CI 0.88-2.03) for prenatal blood lead, 1.30 (95% CI 1.03-1.64) for average childhood blood lead, and 1.48 (95% CI 1.15-1.89) for 6-year blood lead.

The argument isn’t whether lead poisoning leads to violent and potentially criminal behavior, as well as lowered IQs and overall poor health and shortened lives. The argument is whether the banning of leaded gas (and the corresponding overall reduction of lead in the urban environment) is a key factor in the lowering of crime rates. I’m willing to entertain the possibility that this is possible.

The seemingly strongest potential flaw in this hypothesis would seem to be the idea that lead paint in houses should have boosted the crime rate well before leaded gas did. Yet lead paint is typically sequestered in a solid form (and often covered by non-lead-based paint), not generally floating around the atmosphere; furthermore, the lead particles spewed into the air from car exhausts didn’t go away so much as they settled into and mixed with whatever surface dirt and dust blows around the streets. This, combined with the contamination danger from old and now flaking lead paint, helps keep environmental lead levels from declining as quickly as one might expect once both leaded gas and paints were banned. However, even with all of that lead still around, lead poisoning is still on the decline, though it’s still a big problem in places like the Northeast (which would probably have a larger percentage of older housing with lead paint than would, say, Southern California). (It doesn’t help matters that so many kids’ toys and other items, particularly from China, have lead in them.) The fact that crime rates have declined (along with lead poisoning incidences) even though lead-painted interiors and exteriors are still common might actually add strength to the argument that the banning of leaded gas is a big factor in lowered crime rates.

As for the aging population argument as a reason for less crime, that makes sense to me as a potential factor. I’m not sure that inner-city populations are aging (or not dying as young) at the same rate as those elsewhere. (It’s been true for almost as long as statistics have been kept that African-Americans have higher overall mortality rates.) But assuming that this is the case, what would be the main driver of this demographic shift? I’m inclined to think that technological advances are the key factor here: People who would have in the past died from, say, gunshot or stab wounds are kept alive (though sometimes only barely) with increasing frequency. But I also wonder if the slowly declining levels of lead in the inner-city environment may also be a factor in increased longevity — and thus contributing to lower crime rates. Almost certainly not as big a factor, but still perhaps a factor?

Wright is one of the abstracts I linked and which Stormcrow read. Stormcrow would like to see a biochemical explanation for why lead poisoning should lead to an increase in violence.

As for aging of a cohort, any halfway decent statistical analysis takes into account demographic issues. I think it’s a distraction.

As for lead paint vs. leaded gas, I think that the aerosol vs. solid issue is important. Toddlers with nutritional deficiencies/mental disorders may be predisposed to pica. Aerosols affect everyone. Also, lead was delivered as an organic compound, typically tetraethyl lead. Inorganic lead is likely to be much less toxic than organic lead, though I don’t have a specific link.